1. Field of the Invention
The present invention relates to a communication system providing a plurality of different communication services and a method for switching the communication service in this system. More particularly, the present invention relates to a communication system allowing users to switch a communication service with simple operations and a method for switching the communication service.
2. Description of the Related Art
Along with a recent remarkable development in communication technologies, communication services such as, for example, an email service based on an IP (Internet Protocol) network, mobile phone apparatuses using radio communication, and so forth, have become essential not only in business but also in a user's daily life. Furthermore, services so-called an IP phone service and an IP mobile phone service, in which the IP network is utilized as a telephone circuit, have emerged recently. Moreover, a technology for carrying out a videophone service or a videoconference service through the IP network is put into practical use.
As described above, when various communication services are available to a user, the user appropriately selects the most suitable communication service to use. There may be an occasion when the user has to use another communication service, while using one. For example, the users, currently talking on the phone, may desire to continue their talk using a videoconference service instead of the telephony service currently in use.
On this account, some technologies for switching a connection from the in-use communication service to another are offered. For example, a technology for switching the in-use communication service to the most suitable media on the basis of a degree of communication activity, calculated from importance of received information and communication record for each communication partner, is suggested (see, for example, Japanese Unexamined Patent Application Publication No. 2000-112846, paragraph numbers [0054] to [0081] and FIG. 1). A technology to prevent the ongoing communication service from being switched to an unexpected communication media is also suggested. In this technology, a communication terminal station exclusively controls a request for switching a communication media sent from another communication terminal station independently and asynchronously (see, for example, Japanese Unexamined Patent Application Publication No. 1995-177198, paragraph numbers [0025] to [0028] and FIG. 6).